Add -target:<string> fuzzy checking with "Did you mean" message

src/string.cpp

@@ -762,3 +762,42 @@ i32 unquote_string(gbAllocator a, String *s_, u8 quote=0, bool has_carriage_retu
 	}
 	return 2;
 }
+
+
+isize levenstein_distance_case_insensitive(String const &a, String const &b) {
+	isize w = a.len+1;
+	isize h = b.len+1;
+	isize *matrix = gb_alloc_array(heap_allocator(), isize, w*h);
+	for (isize i = 0; i <= a.len; i++) {
+		matrix[i*w + 0] = i;
+	}
+	for (isize i = 0; i <= b.len; i++) {
+		matrix[0*w + i] = i;
+	}
+
+	for (isize i = 1; i <= a.len; i++) {
+		char a_c = gb_char_to_lower(cast(char)a.text[i-1]);
+		for (isize j = 1; j <= b.len; j++) {
+			char b_c = gb_char_to_lower(cast(char)b.text[j-1]);
+			if (a_c == b_c) {
+				matrix[i*w + j] = matrix[(i-1)*w + j-1];
+			} else {
+				isize remove = matrix[(i-1)*w + j] + 1;
+				isize insert = matrix[i*w + j-1] + 1;
+				isize substitute = matrix[(i-1)*w + j-1] + 1;
+				isize minimum = remove;
+				if (insert < minimum) {
+					minimum = insert;
+				}
+				if (substitute < minimum) {
+					minimum = substitute;
+				}
+				matrix[i*w + j] = minimum;
+			}
+		}
+	}
+
+	isize res = matrix[a.len*w + b.len];
+	gb_free(heap_allocator(), matrix);
+	return res;
+}